This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-191716, filed Jun. 25, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a semiconductor device having MIM (Metal Insulating Metal) capacitors. The invention relates also to a method of manufacturing the semiconductor device.
2. Description of the Related Art
Semiconductor devices having MIM (Metal Insulating Metal) capacitors have been provided in recent years.
FIGS. 14 to 16 are sectional views, explaining a method of manufacturing a conventional semiconductor device that has MIS capacitors. The method will be described with reference to FIGS. 14 to 16.
First, via conductors 113 and first wirings 114, made of copper, for example, are formed in the first inter-layer film 111 and second inter-layer film 112 by damascene process, as is illustrated in FIG. 14. Then, a diffusion-preventing film 115 is formed on the second inter-layer film 112, covering the first wirings 114, by means of sputtering.
Thereafter, an MIM capacitor 120 is formed on the diffusion-preventing film 115. The MIM capacitor 120 comprises a lower electrode film 116, a dielectric film 117, and an upper electrode film 119. The films 116, 117 and 119 are laid one on another, in the order they are mentioned.
As FIG. 15 shows, a third inter-layer film 121 is formed on the diffusion-preventing film 115, thus covering the capacitor 120. The third inter-layer film 121 is processed, acquiring a flat and smooth upper surface. A fourth inter-layer film 122 is formed on the third inter-layer film 121. A fifth inter-layer film 123 is formed on the third inter-layer film 122.
RIE (Reactive Ion Etching) is performed on the third, fourth and fifth inter-layer films 121, 122 and 123, forming via holes 124a, 124b and 124c and wiring trenches 125a, 125b and 225c, as is illustrated in FIG. 16. The resultant structure is subjected to annealing using a hydrogen-containing gas.
As FIG. 16 depicts, via conductors 126a, 126b and 126c made of copper are formed in the via holes 124a, 124b and 124c, respectively. Further, second wirings 127a, 127b and 127c, made of copper, too, are formed in wiring trenches 125a, 125b and 125c, respectively. Then, a diffusion-preventing film 128 made of, for example, SiN (silicon nitride) is formed on the fifth inter-layer film 123, covering the second wirings 127a, 127b and 127c. 
In the conventional method, however, annealing using a hydrogen-containing gas is carried out before forming the via conductors 126a, 126b and 126c and the second wirings 127a, 127b and 127c. During the annealing, hydrogen enters the dielectric film 117, inevitably reducing the film 117. Consequently, the permittivity of the film 117 decreases. This results in a decrease in the capacitance of the capacitor 120 and an increase in the leakage current flowing between the electrode films 116 and 119.
According to a first aspect of the present invention, there is provided a semiconductor device that comprises a first electrode film, first and second electrode films, first and second connection parts, first and second wirings, and a protective insulating film. The second electrode film opposes the first electrode film. The capacitor insulating film is provided between the first electrode film and the second electrode film. The first and second connection parts are electrically connected to the first and second electrode films, respectively. The first wiring is electrically connected to the first electrode film by the first connection part. The second wiring is electrically connected to the second electrode film by the second connection part. The protective insulating film is provided between the capacitor insulating film and the second electrode film or on the second electrode film.
According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising a capacitor which has a first electrode film, a second electrode film, and a capacitor insulating film provided between the first and second electrode films. The method comprises: forming a protective insulating film between the capacitor insulating film and the second electrode film or on the second electrode film; forming a insulating film on the capacitor; forming a first trench configured to expose a part of the first electrode film, and a second trench configured to expose a part of the second electrode film; performing heat treatment which uses a hydrogen-containing gas; and forming in the first trench a first connection part electrically connected to the first electrode, and forming in the second trench a second connection part electrically connected to the second electrode film.